With release 217, if you used a world regeneration bomb while standing in a space the bomb is going to regenerate, the bomb would teleport you on the regenerated blocks. This made regeneration bombs safe to use in public farms and could even be used when farming bark. You would “dig” down through the wood, then throw a bomb and get teleported back on top of the tree.
With release 219 this changed. The world regeneration bomb now teleports you on to the highest possible block over the space your standing, not the next possible! This is either the roof of the farm, or the topmost branch of the tree.
But it gets even worse. In my gravel farm, deep below the sea on Besevrona, if you don’t move to the side when regenerating the gravel you’re teleported onto the farm roof… which is conveniently located at the bottom of the sea…
Edit: This does not happen if only one or two layers are regenerated. In that case it behaves as it did with 217 and teleports you onto the generated layers. With 3 or more, it kicks you out of the farm (there are 7 blocks of air between the top of the mud and the roof of the farm)